Dynamic change in amino acids, catechins, alkaloids, and gallic acid in six types of tea processed from the same batch of fresh tea (Camellia sinensis L.) leaves

The manufacturing process plays a crucial role in influencing tea quality by altering its chemical composition. To investigate the effect of different manufacturing processes on the primary chemical components of tea, six types of traditional Chinese tea were produced from the same batch of fresh tea leaves. Dynamic changes of the major chemical components, including 22 free amino acids, 6 catechins, 2 alkaloids, and gallic acid (GA), in those six types of tea and fresh tea leaves, were analyzed. Principal component analysis (PCA) showed fresh tea leaves and the six tea types processed by different methods could be distinguished based on free amino acid chemometric analysis. The content of total free amino acids and catechins drastically decreased during fermentation, whereas GA content increased significantly. The catechin content varied greatly among different types of tea, indicating that epimerization and oxidative degradation of catechins occurred during tea processing. Caffeine content was relatively stable, whereas theobromine content fluctuated slightly according to the production process of the different teas. This study confirmed the dynamic changes in the primary characteristic metabolites during processing of different teas and demonstrated potential biomarkers to monitor the manufacturing process of different teas.